absent directory in find-links causes TOML parse errors: "relative URL without a base"

[garthk]

G'day, again!

UV warns it failed to parse its configuration if find-links = ["dist"] but dist doesn't exist:

$ uv sync
warning: Failed to parse `pyproject.toml` during settings discovery:
  TOML parse error at line 266, column 1
      |
  266 | [tool.uv]
      | ^^^^^^^^^
  relative URL without a base

Resolved 2 packages in 2ms
Audited 1 package in 0.06ms

UV applies the rest of its configuration and continues:

$ uv pip list        
warning: Failed to parse `pyproject.toml` during settings discovery:
  TOML parse error at line 8, column 1
    |
  8 | [tool.uv]
    | ^^^^^^^^^
  relative URL without a base

Package Version
------- -------
cowsay  6.1

Opinions:

• The warning should be shorter than seven lines, and more helpful. Which setting couldn't be parsed? Which line?
• Failure to parse settings should be an error if the setting might have been relevant to the command.

Reproduction script:

cd "$(mktemp -d)"
uv init                                      
printf  >> pyproject.toml  '%s\n' '[tool.uv]' 'find-links = ["dist"]' 'dev-dependencies= ["cowsay"]'
uv sync
uv pip list
uv sync --verbose

Verbose output:

$ uv sync --verbose
warning: Failed to parse `pyproject.toml` during settings discovery:
  TOML parse error at line 8, column 1
    |
  8 | [tool.uv]
    | ^^^^^^^^^
  relative URL without a base

DEBUG uv 0.4.5 (Homebrew 2024-09-04)
DEBUG Found project root: `/tmp/demo`
DEBUG No workspace root found, using project root
DEBUG Reading requests from `/tmp/demo/.python-version`
DEBUG The virtual environment's Python version satisfies `Python 3.12`
DEBUG Using request timeout of 30s
DEBUG Acquired lock for `~/.cache/uv/built-wheels-v3/path/3188e031165e9209`
DEBUG Found static `pyproject.toml` for: tmp-tjwfaj0qd5 @ file:///tmp/demo
DEBUG No workspace root found, using project root
DEBUG Released lock at `~/.cache/uv/built-wheels-v3/path/3188e031165e9209/.lock`
DEBUG Existing `uv.lock` satisfies workspace requirements
Resolved 2 packages in 2ms
DEBUG Using request timeout of 30s
DEBUG Requirement already installed: cowsay==6.1
Audited 1 package in 0.06ms